1. Field of the Invention
This invention relates to a plasma display device, and more particularly to a plasma display device that is adaptive for absorbing an external impact as well as reducing its weight.
2. Description of the Related Art
Generally, a plasma display panel (PDP) is a display device utilizing a visible light emitted from a phosphor layer when an ultraviolet ray generated by a gas discharge excites the phosphor layer. The PDP has an advantage in that it has a thinner thickness and a lighter weight in comparison to the existent cathode ray tube (CRT) and is capable of realizing a high resolution and a large-scale screen. The PDP includes a plurality of discharge cells arranged in a matrix pattern, each of which makes one pixel of a field.
FIG. 1 is a perspective view showing a discharge cell structure of a conventional three-electrode, alternating current (AC) surface-discharge PDP.
Referring to FIG. 1, a discharge cell of the conventional three-electrode, AC surface-discharge PDP includes a first electrode 12Y and a second electrode 12Z provided on an upper substrate 10, and an address electrode 20X provided on a lower substrate 18.
Each of the first electrode 12Y and the second electrode 12Z is a transparent electrode made from indium-tin-oxide (ITO). Since the ITO has a high resistance value, the rear sides of the first and second electrodes 12Y and 12Z are provided with bus electrodes 13Y and 13Z made from a metal, respectively. The bus electrodes 13Y and 13Z supplies a driving signal from the exterior to the first and second electrodes 12Y and 12Z, thereby applying a uniform voltage to each discharge cell.
On the upper substrate 10 provided with the first electrode 12Y and the second electrode 12Z in parallel, an upper dielectric layer 14 and a protective layer 16 are disposed. Wall charges generated upon plasma discharge are accumulated into the upper dielectric layer 14. The protective layer 16 prevents a damage of the upper dielectric layer 14 caused by a sputtering during the plasma discharge and improves the emission efficiency of secondary electrons. This protective layer 16 is usually made from magnesium oxide (MgO).
A lower dielectric layer 22 and barrier ribs 24 are formed on the lower substrate 18 provided with the address electrode 20X. The surfaces of the lower dielectric layer 22 and the barrier ribs 24 are coated with a phosphor layer 26. The address electrode 20X is formed in a direction crossing the first electrode 12Y and the second electrode 12Z.
The barrier rib 24 is formed in parallel to the address electrode 20X to prevent an ultraviolet ray and a visible light generated by a discharge from being leaked to the adjacent discharge cells. The phosphor layer 26 is excited by an ultraviolet ray generated during the plasma discharge to generate any one of red, green and blue visible light rays. An inactive gas for a gas discharge is injected into a discharge space defined between the upper and lower substrate 10 and 18 and the barrier rib 24.
As shown in FIG. 2 and FIG. 3, one side of the panel having a plurality of discharge cells as mentioned above arranged in a matrix type is provided with a heat-radiating plate 30 and a driving circuit board 32 sequentially. A sash 41 is provided to cover the side surface of the panel 40, the heat-radiating plate 30 and a driving circuit board 32.
The driving circuit board 32 is attached to the heat-radiating plate 30 to apply a desired driving signal to the panel 40. To this end, the driving circuit board 32 and the panel 40 is electrically connected to each other by mean of a flexible cable (or flexible printed circuit) as not shown. The sash 41 is provided to enclose the side surface of the panel 40, the heat-radiating plate 30 and the driving circuit board 32, thereby protecting the driving circuit board 32 from an external impact.
The heat-radiating plate 30 is attached to a non-display area of the panel 40 by means of a double-face adhesive tape 36. The heat-radiating plate 30 supports the panel 40 and radiates a heat generated upon driving of the panel 40. Further, the heat-radiating plate 30 plays a role to fix up the driving circuit board 32. To this end, the heat-radiating plate 30 is provided with a plurality of first holes 34a, each of which is passed through by a screw (not shown in FIG. 3) so as to fix the driving circuit board 32 to the heat-radiating plate 30. Further, each end of the heat-generating plate 30 is provided with a plurality of second holes 34b, each of which is passed through by a screw (not shown) so as to fix the heat-radiating plate 30 to the sash 41.
Such a conventional heat-radiating plate 30 is made from aluminum having a high thermal conductivity so that it can effectively radiate a heat generated from the panel 40. However, since a metal of aluminum material fails to absorb or alleviate an impact, it transfers an external impact to the panel as it is. Accordingly, the panel 40 is liable to be damaged by an external impact.
Moreover, the aluminum metal has a heavy weight to cause an increase in total weight of the PDP. Particularly, since a size of the heat-radiating plate 30 is more enlarged as the PDP has larger dimension, a weight of the PDP is more increased. If the PDP has an increased weight, then it has a limit in its installation place. For instance, the PDP is installed at a wall or a ceiling, etc. However, if the weight of the PDP is increased, then the PDP installed at a wall or ceiling may depart from the wall or ceiling to be damaged. Particularly, when the wall or ceiling is made of a material having a weak strength such as wood, the PDP having a heavy weight is liable to depart from the wall or ceiling.